Kinetics of collisionless dissociation of N2F4 in a highpower infrared radiation field

An on-line diagnostic system was used to investigate the kinetics of N₂F₄→2 NF₂ dissociation in a highpower pulsed CO₂ laser field. It was found that, at N₂F₄ pressures of 3–15 Torr and incident energy densities of 0.2–3 J/cm², collisions did not have a significant influence on the excitation and dissociation process and its rate was governed by the rate of radiative activation of the molecules. The intramolecular relaxation time of N₂F₄(τ_ννI < 15) nsec was estimated from the experimental results. The experiment was interpreted satisfactorily assuming that the behavior of N₂F₄ molecules in the field is characterized only by the dependence of the stimulated transition cross section on the molecular energy σ(E) and by the dissociation energy which corresponds to the breaking energy of the weakest N–N bond. The experimental data were used to construct the time dependence of the molecular energy distribution function and to determine the character of the dependence σ(E): σ ~E ^–k(1<k< 2).